Power plant combustion chamber



Jan. 3, 1956 F. o. HENNIG 2,729,052

- POWER PLANT COMBUSTION CHAMBER Filed July 6, 1951llilHlHlllllIIIIIIHIIIHIHHII llllflllll llllliHIIHIHIHNIIIIIHHIIHIIIHIIIHIIIIIIIHIIIIH INVENTOR azyelmg'g ATTO POWER PLANTCOMBUSTION CHAMBER Fritz 0. Hennig, Olean, N. Y., assignor, by mesneassignments, to Dresser Operations, 1110., Whittier, Califi, acorporation of California Application July 6, 1951, Serial No. 235,432

4 Claims. (Cl. 60--39.65)

This invention relates to power plants of the gas turbine type and moreparticularly to the combustion apparatus therefor.

In the copending application of Ward J. Bloomer and Hyman R. Davis,Serial Number 201,415, filed December 18, 1950, now Patent No.2,674,846, there is disclosed a novel form of burner particularlycharacterized by a hollow cylindrical tuyere the side wall of which isprovided with tangentially disposed blades forming a plurality oftangentially disposed air inlets. By passing air under suitable pressurethrough these inlets, a rapidly rotating air column is formed within thetuyere. It has the characteristics of a vortex in that the centrifugaleffect tends to compact the air against the tuyere side wall in thenature of a hollow column and thence to cause the air column todischarge as an annulus from the open end of the tuyere. A low-pressurecentral section is also formed which causes a central gas inflow. In afurnace or combustion gas chamber, this becomes a recycle of hot gases.

The fuel is introduced to this rapidly rotating air vortex to becomevery intimately mixed therewith. The air-fuel mixture is then burned inan adjacent combustion chamber of predetermined diameter and length,thus keeping the tuyere cool. When the combustion chamber, in diameter,does not exceed four times the tuyere outlet diameter, and, in length,is at least approximately as long as it is in diameter, the vorticalmixture of air and fuel will continue to burn in a so-called closedflame pattern of a spiral nature so that high heat release isaccomplished in a very short axial length.

My invention is based on a modification and adaptation of the foregoingtype of combustion apparatus, the whole being generally described as acombustor. I have found that in gas turbine practice, it isindispensible that there be no refractory or other material which canspall, chip, or disintegrate and flow with the gas to the turbine wheel.It is essential with such high speed and high temperature devices thatthere be no impact of particles on the wheel and nothing to causeerosion or corrosion or out-ofbalance conditions.

My invention relates to the construction and operation of a combustionapparatus which is primarily intended to be used with a fuel-air mixingdevice of the vortical tuyere type wherein the combustion chamber may bemade from readily formed sheet metal plates integrated, withoutpermanent bonds, one to another, to form an enclosed combustion chamber,a substantial area of the plates being subject to direct cooling andthus controlled radiation whereby long life is obtainable even at thehigh tempera tures of operation.

A further object of my invention is to provide, in such a combustionchamber, a central cylinder of approximately maximum diameter mountedadjacent the inlet end to maintain a high temperature surface adjacentthe points of impact of the air-fuel mixture discharged from the tuyere,such cylinder being normally maintained at a temperature approaching themaximum combustion ited States Patent chamber temperature wherebydeposit and coalescence of Fig. 2 is a transverse cross-section takensubstantially along the line 22 of Fig. 1.

Fig. 3 is a plan view of a combustion chamber plate.

As generally known, a gas turbine is normally provided with a blower orcompressor for the combustion supporting gas, usually air, a burner ormixer for mixing the air and fuel, a combustion chamber and an airdiluting device. In the present embodiment of my invention, thecombustor including the fuel-air mixer, combustion chamber and dilutingdevice are conveniently mounted in a casing 10. The air, under suitablepressure is supplied to this casing through inlet 12 and the desiredproducts of combustion are discharged at 14 to the turbine. It is to beunderstood that the casing 10 may be vertical or horizontal or at anyother desired angle.

Within the casing 10,.adjacent the air inlet end 12 is V mounted thefuel-air mixer which may be of the specific type described in thecopending application of Bloomer heretofore mentioned. This device,generally indicated at 18, is a hollow, preferably cylindrical, tuyere,the side wall of which is provided with blades 20 which may be stampedout of the wall or otherwise formed to provide tangentially disposed airinlets.

The tuyere 18 is provided with an apertured face plate 21 havingopenings 21a, and 21b, such plate extending to the supporting andenclosing wind box 22. A shield 23 extends over the front of the faceplate and by passing a small amount of air through the openings 21a and21b the tuyere is kept relatively cool. The windbox 22 is supported fromthe casing 10 in a suitable manner as by guide 25. The windbox receivesthe air for combustion which is then directed through the tuyere 18 toestablish the air vortex or hollow column heretofore mentioned.

Fuel may be introduced to this rotating air column in any desiredmanner. Preferably a light fuel such as a distillate or gas may beintroduced through line 28 into the feed pan 30 as hereinafter describedand thence into the air stream as it passes between the blades 20 intothe tuyere Heavier fuels may be introduced through line 32 and theclosed end 18a of the tuyere through one or more nozzles 34. Thesenozzles, if a plurality are used, are interconnected as by a suitabledistributing ring.

A highly effective distribution of the fuel is established by the flowof air through the openings between the blades which picks up the fueland carries it into th internal vortical air column. This fuel-airmixture discharges as an annular column adjacent to the tuyere wall andthus into the combustion chamber 36 in which combustion actually takesplace.

In accordance with a preferred form of embodiment of my invention, thecombustion chamber 36 is of a flexible or non-rigid all-metalconstruction consisting of a plurality of flat plates 38 as particularlyshown in Fig. 3. These may effectively extend the full length of thecombustion chamber 36 and have marginal portions 38a and 38b forattachment and a central portion 380 which, when assembled, will be outof contact with the products of combustion. As will be noted from Fig.2, the marginal portion 38a is partially curved and integrally attachedto the casing 10 as by welding, rivets, etc. It continues to the centralportion 380 which ends at the row of openings 38d. The other marginalportion 38b extends from 3 the openings 38d to the end of the plate 38including the tabs 38c.

As noted in Fig. 2, the tabs 38c on one plate act as an integratingportion and extend into the holes 38d on the adjacent plate thus formingan interconnected polygonal cross-section combustion chamber which isfree to expand and contract with temperature changes. The portions 38cheretofore mentioned are outside of the combustion chamber and in thecooling air stream passing through the casing. These thus provide highcooling rates for the exposed marginal portions 38b which are subject todirect radiation from the flame.

In addition to the flexible combustion chamber, I find it desirable touse the hot ring or sleeve 40 at the inlet end of the combustionchamber. This piece is cylindrical and nearly as large as the innerdiameter of the combustion chamber and of a very high quality of metalthat will withstand continuous flame temperatures. It is notsubstantially cooled by the outside air although ports 42 controlled bya damper 43 may provide more or less air over the outer surface.

It has been found in the burning of fuels having Conradson carboncontents greater than distillate fuels that a cold wall causes prematurecoke deposit. While the reason for this is not fully understood, it maybe due to a partial coalescence and sticking of the liquid droplets.This appears to accumulate at certain spots after which the cokeparticles may break off and carry into the turbine. With the centralsleeve extending over the range of discharge of fuel, such deposits areavoided.

As described in the aforementioned Bloomer application, a closed flamepattern in the combustion chamber is accomplished when the air flowthrough the tuyere inlets is in the order of 50 to 150 feet per sec. Bylimiting the combustion chamber to a maximum of about four times thetuyere diameter, the flame creates both inner and outer eddies in theplane of the axis of the tuyere and combustion chamber. The flamerotation about this axis further emphasizes the formation of thesewhirls or eddies and gives unusual flame stabilization. Indeed, thegreater the issuing velocity, the greater the vortical velocity so thatthe flame may be regarded as stabilizing itself. Substantially completecombustion is thus accomplished in a relatively short length ofcombustion chamber which is at least as long as it is in diameter.

In most turbine practice it is necessary to reduce the temperature ofthe discharge gases to about 1000 F.- 2000" F. depending upon the dutyand this is accomplished by by-passing a substantial part of the inletair through the annular passageway 48 between the combustion chamber 36and the casing 10. A damper may be used to control the amount whichpasses in this manner. This air then passes through the secondary tuyerearrangement shown at 44 and 46.

The secondary tuyere is of the same general construction as the burnertuyere 18 and is especially effective in accomplishing a uniformdilution of the products of cornbustion. As the secondary air fromchannel 48 passes into the tangential openings, it is uniformly diffusedwith the hot products of combustion to establish a uniform temperatureof gas discharge. The secondary tuyere must be carefully formed to avoidthe formation of a vortex which would form a core however and this maybe accomplished by proportioning the air path openings so that there isabout only one third the air velocity through the tuyeres 44 and 46 thatthere is through tuyere 18.

It may also be found desirable to reverse the direction of certain ofthe blades 44 and 46 in the secondary tuyere not only with respect toeach other but also with respect to the blades in the burner. In aparticularly successful operation, the two rows of blades 46 next to thecombustion chamber were oppositely pitched with respect to the burnerblades, and the next adjacent row of blades in tuyere 44 were in thesame direction as the burner blades.

Temperatures at the gas discharge outlet 14 show extremely gooddistribution with average deviation from the mean of only about 10 F. to20 P. where the mean was 1350 F. This is strikingly contrasted withother turbine combustion practice in which variations of about severalhundred degrees from the mean temperature are often found.

While I have shown and described a preferred form of embodiment of myinvention, I am aware that modifications may be made thereto which Iconsider within the scope and spirit of the description herein and theclaims appended hereinafter.

I claim:

1. A power plant combustion chamber comprised of a plurality of plates,each plate extending along the central axis of the chamber and having amarginal portion attached to a support, a central portion normally outof the combustion zone and adapted to be air cooled, and a secondmarginal portion spaced from the first marginal portion by the centralportion, said last mentioned marginal portion forming a part of theinner wall of the combustion chamber and means to secure the marginaledge of one plate to a central portion of another plate wherebyexpansion is provided.

2. A power plant combustion chamber as claimed in claim 1 which saidplates form polygonal surface.

3. A combustion chamber having an air inlet end and a combustionproducts outlet end, comprised of a plurality of plates, each plateextending along the central axis of the chamber and having a marginalportion attached to a support, a central portion normally out of thecombustion zone and adapted to be air cooled, and a second marginalportion spaced from the first marginal portion by the central portion,said last mentioned marginal portion forming a part of the inner wall oftie combustion chamber and means to secure the marginal edge of oneplate to a central portion of another plate and a cylindricalimperforate sleeve concentrically mounted within the plurality of platesat the air inlet end.

4. In combustion with a fuel feeding device, a combustion chamber,having an air inlet end and a combustion products outlet end, comprisedof a plurality of plates, each plate extending along the central axis ofthe chamber and having a marginal portion attached to a support, acentral portion normally out of the combustion zone and adapted to beair cooled, and a second marginal portion spaced from the first marginalportion by the central portion, said last mentioned marginal portionforming a part of the inner wall of the combustion chamber and means tosecure the marginal edge of one plate to a central portion of anotherplate, and an imperforate cylindrical sleeve concentrically mounted inspaced relation with the plurality of plates at the inlet end of saidchamber, said sleeve extending a distance sufiicient to intercept themaximum range of discharge of fuel into said chamber.

References Cited in the file of this patent UNITED STATES PATENTS1,302,950 Muckle May 6, 1919 2,268,464 Seippel Dec. 30, 1941 2,299,154Lair Oct. 20, 1942 2,420,135 Hennig May 6, 1947 2,555,965 Garber June 5,1951 2,575,070 Reed et al. Nov. 13, 1951 2,581,999 Blatz Jan. 8, 19522,616,257 Mock Nov. 4, 1952

